1. Field of the Invention
The present invention relates to an apparatus and method that directly writes or forms a pattern on a photosensitive material such as a substrate, especially, it relates to the positioning of the pattern.
2. Description of the Related Art
An exposure unit with a photolithography function transfers a circuit pattern to a substrate by using a photo-mask or reticle to repeatedly and regularly form a circuit pattern on the total area of a substrate. In the exposure unit, a shot-exposure is repeatedly performed in accordance with the Step & Repeat method. Further, a beam writer that directly writes or forms a pattern without a photo-mask/reticle is also applied. In this case, a light-modulating unit such as a DMD (Digital Micro-mirror Device) or an LCD (Liquid Crystal Device), which has two-dimensionally arrayed light-modulator elements, is utilized instead of a line-scanning.
In the manufacturing process of the substrate, the substrate occasionally deforms due to the heating process. When circuit patterns are regularly and repeatedly formed on the substrate, the deformation of each pattern is different to each other, since the degree of deformation varies with the position of the substrate.
Further, when forming patterns in layers on the substrate by using the exposure unit, the positioning precision is not sufficient, so that a position-error, such as a rotation-error or shift-error, is caused in each pattern.
To correct the position-error of the pattern caused by the deformation, for example, holes are formed in advance such that the holes are positioned at the corners of each pattern, and position-errors between positions of marks formed at a correct position and the position of the holes, are detected for each pattern. Then, the position of the pattern to be formed on the substrate is corrected or modified in accordance with the position-error.